In recent years, the development of small-sized and low-power-consumption image sensors has enabled portable devices, such as PDA (Personal Digital Assistant) and a portable telephone, to have built-in cameras. This makes it possible to take a picture of a printed matter with the built-in camera in stead of a memorandum and send it by e-mail instantaneously. These built-in cameras give top priority to small size, thereby having lower resolution than the usual digital camera.
Generally, the portable terminal device does not have a built-in automatic focusing device because there are limits to the size of a case and the cost. Therefore, it is necessary to achieve proper focusing by confirming a taken image with a display device built into the portable terminal device.
As a focus state display for the autofocus camera, for example, there is a device disclosed in Patent document 1. This device has two or more segments on its display screen, and indicates a focus state with a combination of some segments. Patent document 2 discloses a device that generates differential image data by extracting high spatial frequency components of image data, changes arrangement of color according to values of pixels having high frequency components of this data, and informs a user of a focus state by the difference in colors.
Patent document 1: JP-A No. 96990/1998
Patent document 2: JP-A No. 196225/2002
However, in these conventional portable terminal devices with cameras, since their monitors were too small to check the focus state, it was difficult to pick up correctly focused images.
That is, since the display device built into the portable terminal device was small and had a small number of pixels, when the user tried to achieve proper focusing by judging blurring of an image on the monitor with the naked eye, the focus state was unclear, and consequently the user hardly achieved proper focusing.
This invention is devised in view of such a problem, and has as object to provide a focus state display, a portable terminal device, an information indication program, and its program whereby the user can easily judge the focus state of a camera and can easily perform confirmation/adjustment of an in-focus state.